Method for the preparation of phenolsulfide stabilizers

ABSTRACT

A METHOD OF PREPARING SUBSTITUTED PHENOLSULFIDES BY REACTING A MIXTURE OF TERT-BUTYL CRESOLS WITH SULFUR DICHLORIDE IN AN ORGANIC SOLVENT SUCH AS BENZINE, WHITE SPIRIT AND PETROLEUM ETHER.

United States Patent O 3,553,269 METHOD FOR THE PREPARATION OF PHENOLSULFIDE STABILIZERS Henry Hugh Richmond, Leninsky prospekt 86, kv. 319, and Elena Vasilievna Pronina, Ul. Gorkogo 8, korp. 2, kv. 38, both of Moscow, USSR. No Drawing. Filed Feb. 28, 1967, Ser. No. 619,201 Int. Cl. C07c 149/38; C08f 45/58 US. Cl. 260-609 6 Claims ABSTRACT OF THE DISCLOSURE A method of preparing substituted phenolsulfides by reacting a mixture of tert-butyl cresols with sulfur dichloride in an organic solvent such as benzine, white spirit and petroleum ether.

BACKGROUND OF INVENTION The present invention relates to a method of preparing substituted phenolsulfide stabilizers for polymeric materials such as raw rubber, vulcanized rubber, polyethylene and other oxidizable products. Theknown method of preparing the stabilizer 1,1-bis (4-hydroxy 2 methyl-5-tert-butylphenyl) sulfide comprises the reaction of 6-tert-butyl-m-cresol with sulfur dichloride in a carbon tetrachloride medium.

However, 6-tert-butyl-m-cresol in an expensive product since it. is prepared from pure m-cresol. m-Cresol, in its own right, is also an expensive product since it is diificult to separate it from its mixtures with mand pcresol, with which it is produced since their boiling points are very close. The main object of the preset invention is the preparation of crystalline 1,1-bis (4-hydroxy-2-methyl-5-tertbutylphenyl) sulfide from a cheaper starting material than 6-tert-butyl-m-cresol.

Another object of the invention is the development of a simple and effective method for the preparation of stabilizers for polymeric materials.

Still another object'of the invention is the utilization of by-products obtained in the manufacture of 2,6-ditert-butyl phenol, known also as Ionol.

SUMMARY OF THE INVENTION The above mentioned and other objects are achieved by a' new method for the preparation of substituted phenolsulfide stabilizers for polymeric and other oxidizable products. This method comprises the reaction of a mixture of tert-butyl cresols with sulfur dichloride in an organic solvent. In accordance with the method of invention, as a source of tert-butyl cresols there is utilized a mixture of'alkylated cresols and alkylated substituted phenols containing 6-tert-butyl-m-cresol and Z-tert-butylp-creso l. The process is carried out in a medium comprising a hydrocarbon solvent of the paraffin or cycloaliphatic series or their mixtures. After the reaction, the desired product is separated from the reaction mixture by filtration or by distilling off the solvent.

In the above mentioned solvents crystalline 1,1-bis '(4-hydroxy 2-methyl-S-tert-butylphenyl) sulfide precipitates out as it is formed. Using carbon tetrachloride as a solvent does not permit of such a separation step.

' Depending on the method of separating the final prod- "ice net, the latter may be obtained as relatively pure crystalline 1,1-bis (4-hydroxy-2-methyl S-tert-butylphenyl) sulfide or in the form of a viscous, non-crystalline mass, i.e. a mixture of 1,1-bis (4-hydroxy-2-methyl-S-tert-butylphenyl) sulfide with other substituted phenolsulfides.

The crystalline product is obtained by filtering oh the precipitate that appears in the reaction mixture. By distilling off the solvent from the mother liquor, there is obtained a non-crystalline mass which also is an effective stabilizer.

As a hydrocarbon solvent there may be used various fractions of benzine, white spirit or petroleum ether.

DETAILED DESCRIPTION OF INVENTION For the preparation of the stabilizer, there may be used a mixture of 6-tert butyl-m-cresol and 2-tert-butylp-cresol and other alkylated phenols. The above mentioned mixture of 6-tert-butyl-m-cresol and Z-tert-butylp-cresol may be obtained by the alkylation of commercial mand p-cresol, which contains such impurities as ethyl phenol and xylenols, with isobutylene, to the point where the product contains predominantly mono-tertbutyl cresols.

This mixture may also be obtained by the extraction of by-products formed in the manufacture of 2,6-di-tertbutyl phenol (Ionol).

The proposed invention enables the simplification at a decreased cost of the method of preparing 1,1-bis (4- hydroxy 2-methy1 S-tert-butylphenyl) sulfide because the starting material is not relatively pure 6-tert-butylrn-cresol but its mixture with other alkylated cresols. In this way, the complex process of separating meta and para cresol is unnecessary in order to obtain pure mcresol and from the latter, 6-tert-butyl-m-cresol.

The invention enables one to obtain in addition to a crystalline product, a mixture of products consisting of 1,1-bis (Z-hydroxy-3-tert-butyl S-methylphenyl) sulfide, 1,1-bis (4-hydroxy-2-methyl S-tert-butylphenyl) sulfide and 1-(2-hydroxy 3 tert-butyl-6-methylphenyl-1-(4-hydroxy S-tert-butyl Z-methylphenyl) sulfide all of which are stabilizers for polymeric materials and other oxidizable materials.

EXAMPLE 1 To a three necked flask, provided with a stirrer, reflux condenser and a dropping funnel there is added 20 g. (0.122 mole) of a mixture consisting of -tert-butyl-mcresol and Z-tert-butyl-p-cresol dissolved in purified white spirit. To the solution, there is added with stirring and cooling with a water bath over a period of minutes a solution of 6.9 g. (0.067 mole) of sulfur dichloride in 60 ml. white spirit. Then the mixture is mixed for a period of 60-80 -minutes until the color of the sulfur dichloride disappears. The mixture is then blown with nitrogen for a period of 1-2 hours to remove the hydrogen chloride formed during the reaction. The white precipitate that forms is filtered off and dried to constant weight. The yield of 1,1-bis (4-hydroxy-Z-methyl-S-tertbutylphenyl) sulfide M.P. -152 C. amounts to 11.0 11.9 g. or 5054% of theory. The mother liquor is evaporated at 10 mm. Hg to yield a viscous mass which is further dried in a vacuum oven to a constant weight of 11.3-12.3 g. which also is an effective stabilizer. The yield of 50-54% is arbitrarily based on all the butyl cresols present; actually the yield is much higher since some of the butyl cresol is Z-tert-butyl-p-cresol.

EXAMPLE 2 at a temperature of 160" C. for a period of 6 hours using To a threemecked flask, equipped with an efficient a stabilizer concentration of 0.01 mole per kg. of polystirrer, reflux condenser and dropping funnel there is ethylene. The results of the tests are given 1n Table 1. dd d 393 (243 moles) f a mixture Consisting f For comparison, the results obtained in testing the above tert-butyl-m-cresol and Z-tertbutyl-p-cresol. This mixture Polyethylene types With a Commercial Sample of 1,1"biS was isolated from a fraction boiling between cresol and (4-hydroxy-2-methyl-S-tert-butylphenyl) sulfide are also Ionol obtained as a by-product in the manufacture of given.

TABLE 1 Properties of the polyethylene after milling 1 hour 2 hours 4 hours 6 home E, E, Type of polymer Stabilizer percent tan 17 percent tan a percent tan a percent tan a High pressure p0lyetllylene. crggstallinle sltabilizer obtained according to 438 0.0009 398 0.0007 362 0. 0009 392 0.0009

xamp e Without stabilizer 478 0. 0009 194 0. 0040 98 0. 0107 76 0. 0107 Low pressure polyethylene Non-crystalline stabilizer from the mother 650 0.0005 658 0.0004 632 0.0004 572 0.0003

liquor according to Example 1. Commercial 1,1-bis (4-hydroxy-2-methyl-5- 674 0, 0003 610 0.0003 600 0.0003

tert butyl phenyl) sulfide. Without stabilizer 807 0.00025 12 0,0026 4 0.0109

Ionol. There is also added 1500 ml. of petroleum ether. In Table 1, E, percent designates the relativeelongation To the resulting solution there is added with constant in percent and tan a, the dissipation factor at a frequency stirring and cooling with a water bath to 2030 C., of 10 c.p.s. over a period of 2 hours 125.1 g. (1.22 moles) of sulfur From the table it is clear, that the substituted phenoldichloride in 1000 ml. of petroleum ether. Then the mixsulfides obtained by the proposed process are effective ture is stirred until the color of sulfur dichloride disapstabilizers of high and low pressure polyethylene. Unstapears. The solvent is distilled off and the viscous residue bilized polyethylene even after two hours milling shows which consists of a mixture of substituted phenolsulfide is a greatly decreased relative elongation (E, percent) and used as a stabilizer for polymeric materials. an increased dissipation factor.

The stabilizers obtained by the proposed method were EXAMPLE 3 tested in the stabilization of polypropylene fiber in air at To a three-necked flask, equipped with an efiicient 150 C. for a period of 16 hours and with radiation with stirrer, reflux condenser and dropping funnel, there is ultraviolet light at a temperature of 90 C. for a period added 400.1 g. (2.469 moles) of amixture of G-tert-butylof 20 hours. The physical and mechanical properties of m-cresol and Z-tert-butyl-p-cresol and 1500 ml. of petrothe fiber before and after testing are given in Table 2.

TABLE 2 Physicial and Mechanical Properties of fiber Initial After heating to 150 After irradiationwith ultravioletlight Amount Relative Residual Relative Residual stabilizer Tensile Relative Tensile elongation tensile Tensile elongation tensile Expt. introduced, strength, elongation, strength, retained, strength, strength, retained, strength, N o. Stabilizer percent km. percent km. percent percent km. percent percent 1 Without stabilizer 34.2 32.3 2 Crystalline stabilizer ob- 0.5 43. 6 26.3 26.3 61. 0 60. 3 33. 7 38.0 77. 0

tained in Example 1. 3 Commereialbis(4-hydr0xy- 0.5 23.0 21. 5

4 Stabilizer obtained in 0. 5 45.8 24. 9 21.8 89. 0 47. 5 33. 8 v 38. 0 73. 5

Example 3.

5 Stabilizer obtained from 0. 5 43. 8 22. 8 25. 9 61. 9 59. 0 37. 9 28. 0 86. 0

the mother liquor of Example 1.

1 Fiber disintegrates after 3-4 hours. 2 Fiber disintegrates.

leum ether. To the solution formed, with stirring and What is claimed is:

cooling on a water bath to 2030 C. there is added over 1. A method for preparation of substituted phenolthree hours a solution of 150.4 g. (1.460 moles) of sulsulfide stabilizers for polymers and other oxidizable matefur dichloride dissolved in 1000 ml. of petroleum ether. rials comprising reacting a mixture of impure 6-tert-butyl- The reaction mixture is reacted with stirring another 6-7 m-cresol and Z-tert-butyl-p-cresol with sulfur dichloride in hours until the color of the sulfur dichloride disappears, a hydrocarbon solvent selected from the group consisting and then the solvent is distilled off with steam. The prodof benzine, while spirit and petroleum ether, the ratio of not after the removal of the solvent is dried to constant solvent to alkylated phenol starting materials being from weight. The weight of product, which consists of a mixabout 3:1 to about 6:1 and separating 1,1-bis(4-hydroxyture of substituted phenolsulfides in the form of a yellow Z-methyl-S-tert-butylphenyl)sulfide as a product from the non-crystalline mass amounts to 474.8 g. reaction medium;

Although the present invention is described in terms 2. A method according to claim 1, wherein they product of a preferred Way of carrying it out, it will be underis'obtained in crystalline form from the reaction mixture stood, by those skilled in the art, that changes and modiby filtering the precipitate from the mother liquor. fications can be made without altering the idea and scope '3. 'A method according to claim 2, wherein the solvent of the invention. is distilled off from mother liquor.

These changes and modifications should be considered 4. A method according to claim 1, wherein the isolaas falling within the true spirit and scope of the invention tion of the product from the reaction mixture is effected as defined by appended claims. by distilling off the solvent.

Substiuted phenolsulfides obtained by the proposed 5. A method according to claim 1 wherein said hydromethod were tested as stabilizers for polyethylene made carbon solvent is selected from the group consisting of by the high pressure method and the low pressure method benzine, white spirit and petroleum ether.

6 6. A method according to claim 1 wherein said mix- FOREIGN PATENTS ture of impure 6-tert-butyl-m-cresol and 2-tert-butyl-p- 188 965 1/1966 USS-K 260 609 cresol additionally contains butylated phenols produced n by the alkylation of dicresol with isobutylene. CHARLES B P ARKER, p i Examiner References Cited 5 D. -R. PHILLIPS, Assistant Examiner UNITED STATES PATENTS CL XER- 2,346,826 4/1944 Cook et a1 260609 1 .60-45.95 3,069,384 12/1962 Cofiield 260--609X 3,326,800 6/1967 Cofiield 260609X 10 

